v0.3.1 (2022-09-09)

  • encode_body: Set Accept header in JSON requests
  • put_base_url: Fix merging with leading and/or trailing slashes
  • Fix merging :adapter option
  • Add get/2, post/2, put/2, patch/2, delete/2 and head/2


v0.3.0 (2022-06-21)

Req v0.3.0 brings redesigned API, new steps, and improvements to existing steps.



The new API allows building a request struct with all the built-in steps. It can be then piped to functions like Req.get!/2:

iex> req = "")

iex> req |> Req.get!(url: "/repos/sneako/finch") |> then(& &1.body["description"])
"Elixir HTTP client, focused on performance"

iex> req |> Req.get(url: "/repos/elixir-mint/mint") |> then(& &1.body["description"])
"Functional HTTP client for Elixir with support for HTTP/1 and HTTP/2."

Setting body and encoding it to form/JSON is now done through :body/:form/:json options:

iex>!("", body: "hello!").body["data"]

iex> req = "")
iex>!(req, form: [x: 1]).body["form"]
%{"x" => "1"}
iex>!(req, json: %{x: 2}).body["form"]
%{"x" => 2}


Improved Error Handling

Req now validates option names ensuring users didn't accidentally mistyped them. If they did, it will try to give a helpful error message. Here are some examples:

Req.request!(urll: "")
** (ArgumentError) unknown option :urll. Did you mean :url? "")
** (ArgumentError) unknown option :bas_url. Did you mean :base_url?

Req also has a new option to handle HTTP errors (4xx/5xx). By default it will continue to return the error responses:

#=> %Req.Response{status: 404, ...}

but users can now pass http_errors: :raise to raise an exception instead:

Req.get!("", http_errors: :raise)
** (RuntimeError) The requested URL returned error: 404
Response body: ""

This is especially useful in one-off scripts where we only really care about the "happy path" but would still like to get a good error message when something unexpected happened.



From the very beginning, Req could be extended with custom steps. To make using such custom steps by others even easier, they can be packaged up into plugins.

Here are some examples:

And here's how they can be used:

  {:req, "~> 0.3.0"},
  {:req_easyhtml, github: "wojtekmach/req_easyhtml"},
  {:req_s3, github: "wojtekmach/req_s3"},
  {:req_hex, github: "wojtekmach/req_hex"},
  {:req_github_oauth, github: "wojtekmach/req_github_oauth"}

req =
  ( :raise)
  |> ReqEasyHTML.attach()
  |> ReqS3.attach()
  |> ReqHex.attach()
  |> ReqGitHubOAuth.attach())

Req.get!(req, url: "").body[".entry-summary h5"]
# #EasyHTML[<h5>
#    Elixir is a dynamic, functional language for building scalable and maintainable applications.
#  </h5>]

Req.get!(req, url: "s3://ossci-datasets").body
# [
#   "mnist/",
#   "mnist/t10k-images-idx3-ubyte.gz",
#   "mnist/t10k-labels-idx1-ubyte.gz",
#   "mnist/train-images-idx3-ubyte.gz",
#   "mnist/train-labels-idx1-ubyte.gz"
# ]

Req.get!(req, url: "").body["metadata.config"]["links"]
#=> %{"GitHub" => ""}

Req.get!(req, url: "").body["login"]
# Outputs:
# paste this user code:
#   6C44-30A8
# at:
# open browser window? [Yn]
# 15:22:28.350 [info] response: authorization_pending
# 15:22:33.519 [info] response: authorization_pending
# 15:22:38.678 [info] response: authorization_pending
#=> "wojtekmach"

Req.get!(req, url: "").body["login"]
#=> "wojtekmach"

Notice all plugins can be attached to the same request struct which makes it really easy to explore different endpoints.

See "Writing Plugins" section in Req.Request module documentation for more information.


Plug Integration

Req can now be used to easily test plugs using the :plug option:

defmodule Echo do
  def call(conn, _) do
    "/" <> path = conn.request_path
    Plug.Conn.send_resp(conn, 200, path)

test "echo" do
  assert Req.get!("http:///hello", plug: Echo).body == "hello"

you can define plugs as functions too:

test "echo" do
  echo = fn conn ->
    "/" <> path = conn.request_path
    Plug.Conn.send_resp(conn, 200, path)

  assert Req.get!("http:///hello", plug: echo).body == "hello"

which is particularly useful to create HTTP service mocks with tools like Bypass.


Request Adapters

While Req always used Finch as the underlying HTTP client, it was designed from the day one to easily swap it out. This is now even easier with an :adapter option.

Here is a mock adapter that always returns a successful response:

adapter = fn request ->
  response = %Req.Response{status: 200, body: "it works!"}
  {request, response}

Req.request!(url: "http://example", adapter: adapter).body
#=> "it works!"

Here is another one that uses the json/2 function to conveniently return a JSON response:

adapter = fn request ->
  response = Req.Response.json(%{hello: 42})
  {request, response}

resp = Req.request!(url: "http://example", adapter: adapter)
#=> [{"content-type", "application/json"}]
#=> %{"hello" => 42}

And here is a naive Hackney-based adapter and how we can use it:

hackney = fn request ->
  case :hackney.request(
       ) do
    {:ok, status, headers, body} ->
      headers = for {name, value} <- headers, do: {String.downcase(name), value}
      response = %Req.Response{status: status, headers: headers, body: body}
      {request, response}

    {:error, reason} ->
      {request, RuntimeError.exception(inspect(reason))}

Req.get!("", adapter: hackney).body["description"]
#=> "Elixir is a dynamic, functional language designed for building scalable and maintainable applications"

See "Adapter" section in Req.Request module documentation for more information.


Major changes


Step changes

  • New step: put_plug

  • New step: put_user_agent (replaces part of removed put_default_headers)

  • New step: compressed (replaces part of removed put_default_headers)

  • New step: compress_body

  • New step: output

  • New step: handle_http_errors

  • put_base_url: Ignore base URL if given URL contains scheme

  • run_finch: Add :connect_options which dynamically starts (or re-uses already started) Finch pool with the given connection options.

  • run_finch: Replace :finch_options with :receive_timeout and :pool_timeout options

  • encode_body: Add :form and :json options (previously used as {:form, data} and {:json, data})

  • cache: Include request method in cache key

  • decompress_body, compressed: Support Brotli

  • decompress_body, compressed: Support Zstandard

  • decode_body: Support decode_body: false option to disable automatic body decoding

  • follow_redirects: Change method to GET on 301..303 redirects

  • follow_redirects: Don't send auth headers on redirect to different scheme/host/port unless location_trusted: true is set

  • retry: The Retry-After response header on HTTP 429 responses is now respected

  • retry: The :retry option can now be set to :safe (default) to only retry GET/HEAD requests on HTTP 408/429/5xx responses or exceptions, :always to always retry, :never to never retry, and fun - a 1-arity function that accepts either a Req.Response or an exception struct and returns boolean whether to retry

  • retry: The :retry_delay option now accepts a function that takes a retry count (starting at 0) and returns the delay. Defaults to a simple exponential backoff: 1s, 2s, 4s, 8s, ...



  • Deprecate calling!(url, body) in favour of!(url, body: body). Also, deprecate!(url, {:form, data}) in favour of!(url, form: data). and!(url, {:json, data}) in favour of!(url, json: data). Same for Req.put!/2.

  • Deprecate setting retry: [delay: delay, max_retries: max_retries] in favour of retry_delay: delay, max_retries: max_retries.

  • Deprecate setting cache: [dir: dir] in favour of cache_dir: dir.

  • Deprecate in favour of manually building the struct.


v0.2.2 (2022-04-04)

  • Relax Finch version requirement


v0.2.1 (2021-11-24)

  • Add :private field to Response
  • Update Finch to 0.9.1


v0.2.0 (2021-11-08)

  • Rename normalize_headers to encode_headers
  • Rename prepend_default_steps to put_default_steps
  • Rename encode and decode to encode_body and decode_body
  • Rename netrc to load_netrc
  • Rename finch step to run_finch
  • Rename if_modified_since to put_if_modified_since
  • Rename range to put_range
  • Rename params to put_params
  • Rename request.uri to request.url
  • Change response/error step contract from f(req, resp_err) to f({req, resp_err})
  • Support mime 2.x
  • Add Req.Response struct
  • Add put!/3 and delete!/2
  • Add run_steps/2
  • Initial support for UNIX domain sockets
  • Accept {module, args} and module as steps
  • Ensure get_private and put_private have atom keys
  • put_default_steps: Use MFArgs instead of captures for the default steps
  • put_if_modified_since: Fix generating internet time
  • encode_headers: Encode header values
  • retry: Rename :max_attempts to :max_retries


v0.1.1 (2021-07-16)

  • Fix append_request_steps/2 and prepend_request_steps/2 (they did the opposite)
  • Add finch/1


v0.1.0 (2021-07-15)

  • Initial release